hard crash when naming event :transition

[kjwierenga]

Apparently :transition is not a valid event name. Rather than crashing the ruby interpreter it would be nice to get an exception.

require 'finite_machine'

fsm = FiniteMachine.define do
  event :transition, :a => :b
end

fsm.transition

$ ruby examples/finite_machine/callbacks.rb 
/Users/kjw/.rvm/gems/ruby-1.9.3-p484@fsmtalk/gems/finite_machine-0.6.1/lib/finite_machine/transition.rb:130: [BUG] Segmentation fault
ruby 1.9.3p484 (2013-11-22 revision 43786) [x86_64-darwin12.5.0]

-- Control frame information -----------------------------------------------
c:2657 p:0018 s:9297 b:7969 l:001468 d:007968 LAMBDA /Users/kjw/.rvm/gems/ruby-1.9.3-p484@fsmtalk/gems/finite_machine-0.6.1/lib/finite_machine/transition.rb:130
c:2656 p:---- s:7965 b:7965 l:007964 d:007964 FINISH

It looks like this code results in infinite recursion.